To provide legal security in property rights/land tenure and support efficient land use planning, one needs a well-functioning system of land administration. In other words good land administration is the basis for sustainable land management and a stable and efficient land market.

Although property rights and procedures vary considerably between jurisdictions, the underlying data model to support land administration was found to be quite similar. Therefore, a decade ago, several of the authors of this paper initiated the process of coming to an international reference standard for land administration, the so-called Land Administration Domain Model (LADM). LADM is a framework for describing interest in land according to internationally agreed concepts and terminology and makes it possible to categorize interests in land (in specific jurisdiction) regardless of the origin in different legal systems. This not only enables the improvement and further development of national systems of land administration, but also supports international communication and exchange of data. In 2012 the LADM became an international standard, ISO 19152.

The LADM is based on “right”, “restriction” and “responsibility” (RRR) classes, which can apply to land, but also to buildings, network utilities, and 3D volumetric spatial units. Based on a number of earlier publications, such as (Paasch 2012), (Paasch et al 2013) and (Hespanha et al 2013), this paper explores the need and possible approaches to a more detailed classification of property rights, by either adding more subclasses for specific sets of RRRs, clustered after their legal or societal characteristics (e.g. common rights, latent rights, customary rights or informal rights as explored by (Paasch et al 2013)) or by the extension of code list values in LADM for a more refined classifications, or both. Options to ‘define’ code list values are: 1. describe with natural text, or 2. additionally encode an hierarchical structure to code list values, or 3. develop an ontology of the code list values, such as ownership, lease, etc. However, in all options it is non-trivial to define formally basic legal concepts such as ‘ownership’.

We will further investigate these aspects, including the decision when to add new classes and when to extend the code list values. In case of code list it will be further explored what is good approach to define the values.